linux-kernel - [PATCH 2/2] selftests/mm/uffd-stress: Stricten constraint on free hugepages before the test

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Message-Id: <20250826070705.53841-3-dev.jain@arm.com>
Date: Tue, 26 Aug 2025 12:37:05 +0530
From: Dev Jain <dev.jain@....com>
To: akpm@...ux-foundation.org,
	david@...hat.com,
	shuah@...nel.org
Cc: lorenzo.stoakes@...cle.com,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	rppt@...nel.org,
	surenb@...gle.com,
	mhocko@...e.com,
	npache@...hat.com,
	ryan.roberts@....com,
	linux-mm@...ck.org,
	linux-kselftest@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Dev Jain <dev.jain@....com>
Subject: [PATCH 2/2] selftests/mm/uffd-stress: Stricten constraint on free hugepages before the test

The test requires at least 2 * (bytes/page_size) hugetlb memory, since
we require identical number of hugepages for src and dst location. Fix
this.

Along with the above, as explained in patch "selftests/mm/uffd-stress:
Make test operate on less hugetlb memory", the racy nature of the test
requires that we have some extra number of hugepages left beyond what is
required. Therefore, stricten this constraint.

Fixes: 5a6aa60d1823 ("selftests/mm: skip uffd hugetlb tests with insufficient hugepages")
Signed-off-by: Dev Jain <dev.jain@....com>
---
 tools/testing/selftests/mm/uffd-stress.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
index 40af7f67c407..eb0b37f08061 100644
--- a/tools/testing/selftests/mm/uffd-stress.c
+++ b/tools/testing/selftests/mm/uffd-stress.c
@@ -449,7 +449,7 @@ int main(int argc, char **argv)
 	bytes = atol(argv[2]) * 1024 * 1024;
 
 	if (test_type == TEST_HUGETLB &&
-	   get_free_hugepages() < bytes / page_size) {
+	   get_free_hugepages() < 2 * (bytes / page_size) + 10) {
 		printf("skip: Skipping userfaultfd... not enough hugepages\n");
 		return KSFT_SKIP;
 	}
-- 
2.30.2